The present disclosure relate to fuel system valves, and particularly to a roll-over valve for closing a venting passageway in a vehicle fuel system if the vehicle is rolled over in an accident or tilted during braking and cornering. More particularly, the present disclosure relates to a vent closure valve including an overfill protection system for preventing overfilling of a fuel tank equipped with one or more roll-over valves and a vacuum-relief system for relieving unwanted vacuum conditions in a fuel tank.
Vehicle fuel systems are known to include pressure-relief roll-over valves that are mountable on either the fuel tank or the filler neck of the vehicle. These roll-over valves are configured to permit fuel vapor to vent from the fuel tank when the vehicle is operating normally, and to prevent fuel from spilling from the fuel tank through the vent when the vehicle is tilted a preselected amount, or is rolled over in an accident. A roll-over valve should be equipped to accommodate a substantial flow rate of fuel vapor from the fuel tank because of the large size of many fuel tanks, and because of the volatility of certain blends of fuel.